For centuries, the church has been making everything out of gold. I guess it's because the things in the church are for God, so they must be of the finest quality.
(someone tell me how to have the former post placed in italics, please)
From http://www.newadvent.org/cathen/03561a.htm
The chalice must not be made of brass or copper, because it generates rust (i. e. verdigris) which causes nausea.
(in the same article)
According to the existing law of the Church the chalice, or at least the cup of it, must be made either of gold or of silver, and in the latter case the bowl must be gilt on the inside. In circumstances of great poverty or in time of persecution a calix stanneus (pewter) may be permitted, but the bowl of this also, like the upper surface of the paten, must be gilt. Before the chalice and paten are used in the Sacrifice of the Mass they require consecration.
Anyone here a chemist? Isn't there some medicinal reason for using gold lined cups with the wine?
Gold is incorruptible. That is why it is used. Nothing can pass through it, plus it's very stable. Every care must be taken with the Body and Precious Blood to the point where the wine is poured now before either elevation, just to be sure.
As an aside, gold is also a main theme of Revelation. Just food for thought.
And as he spake, a certain Pharisee besought him to dine with him: and he went in, and sat down to meat. And when the Pharisee saw it, he marvelled that he had not first washed before dinner. And the Lord said unto him, Now do ye Pharisees make clean the outside of the cup and the platter; but your inward part is full of ravening and wickedness. -Luke 11:37-39